targetcli causes calltrace with the particular partition names which include 2 digits.

Issue

• targetcli causes calltrace with the particular partition names which include 2 digits.
  For example, create block device with sda10 and run 'ls' in targetcli.

  utils.py:90:fread:IOError: [Errno 2] No such file or directory: '/sys/block/sda1/sda10/size'
  
  Traceback (most recent call last):
    File "/bin/targetcli", line 121, in <module>
      main()
    File "/bin/targetcli", line 111, in main
      shell.run_interactive()
    File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 894, in run_interactive
      self._cli_loop()
    File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 723, in _cli_loop
      self.run_cmdline(cmdline)
    File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 837, in run_cmdline
      self._execute_command(path, command, pparams, kparams)
    File "/usr/lib/python2.7/site-packages/configshell_fb/shell.py", line 812, in _execute_command
      result = target.execute_command(command, pparams, kparams)
    File "/usr/lib/python2.7/site-packages/configshell_fb/node.py", line 1411, in execute_command
      return method(*pparams, **kparams)
    File "/usr/lib/python2.7/site-packages/configshell_fb/node.py", line 710, in ui_command_ls
      tree = self._render_tree(target, depth=depth)
    File "/usr/lib/python2.7/site-packages/configshell_fb/node.py", line 861, in _render_tree
      + self._render_tree(children[i], margin, depth)
    File "/usr/lib/python2.7/site-packages/configshell_fb/node.py", line 765, in _render_tree
      (description, is_healthy) = root.summary()
    File "/usr/lib/python2.7/site-packages/targetcli/ui_backstore.py", line 540, in summary
      return ("%s (%s) %s%s %s" % (so.udev_path, bytes_to_human(so.size),
    File "/usr/lib/python2.7/site-packages/rtslib_fb/tcm.py", line 703, in _get_size
      return get_size_for_disk_name(self._parse_info('device')) * int(self._parse_info('SectorSize'))
    File "/usr/lib/python2.7/site-packages/rtslib_fb/utils.py", line 162, in get_size_for_disk_name
      return get_size("/sys/block/%s/%s" % (disk, m.group()), True)
    File "/usr/lib/python2.7/site-packages/rtslib_fb/utils.py", line 141, in get_size
      sect_size = int(fread("%s/size" % path))
    File "/usr/lib/python2.7/site-packages/rtslib_fb/utils.py", line 90, in fread
      with open(path, 'r') as file_fd:
  IOError: [Errno 2] No such file or directory: '/sys/block/sda1/sda10/size'
  
  Local variables in innermost frame:
  path: '/sys/block/sda1/sda10/size'